Utilizing a 4 pound fully automatic portable blood pressure recorder with a conventional sphygmomanometer cuff, a group of hypertensives (essential, labile, renal types) will have their blood pressures and heart rates recorded at 15 minute intervals during an 8 hour period while engaged in their usual work activities. A voice channel allows the subject to dictate with each pressure recording, the time, whether standing, sitting or lying, his physical activity, his emotional state and any physical symptoms. Such recordings will be made prior to and during treatment with single or multiple antihypertensive agents. Similar recordings at work will be made for apparently healthy controls, not on medications, of comparable age and sex. Where possible and feasible, some patients and controls will have 24 hour recordings including sleep at home. As a pilot study, a smaller group of patients and controls will also have attached a Holter monitor (continuous ECG recording) during the 8 hour pressure recordings to identify any correlations between pressures, heart rates, arrhythmias and evidence of transient myocardial ischemia with their activities, their physical and their emotional states. Such data would be unique and of great potential value in understanding blood pressure behavior in normals and hypertensives and the benefits and side effects of chemical treatment in the latter group.